Over the past decade, the MRSA infection has gradually spread and infection rate has rapidly increased in hospitals and nursing homes, where patients with open wounds, invasive devices, and weakened immune systems are at greater risk of infection than the general public. The Methicillin-Resistant Staphylococcus Aureus base camp turns out to be hospitals around the world.
As shown by the monitoring data in Europe, the United States and Asian countries, the infection prevalence in Nordic countries and the Netherlands is below 5%, that in the United States is up to an average of 52%, in Asia's Taiwan, Japan, South Korea and China, the prevalence is over 50%. These show that MRSA and other medicine resistant bacteria are the prime culprit of today's nosocomial infections in the world.
Owning to the spread of MRSA in the hospitals, not only patients are threatened, but also huge losses for hospitals, communities and the country are caused. About 2 million people nosocomial infections in the United States each year cause 100,000 deaths, and cost $40 billion, equivalent to the total number of deaths and to total expenditures caused from breast cancer, AIDS and traffic accidents. Every year, around 3 million people in the EU catch a healthcare-associated infection, resulting in approximately 50,000 deaths.
Various countermeasures or solutions to improve and clean the living environment have been proposed to prevent a variety of bacteria spreading in the medical institutions, wherein one of the countermeasures is the hospital medical textile products, such as: hospital ward coverlets, beddings and pillows, as well as uniforms of medical staffs, or clothings of chronic disease stricken or critically ill patients in long-term care units to be changed into the use of antibacterial textiles, to deal with the rampant terror of MRSA and other medicine resistant bacteria (also known as super bacteria).
As for antibacterial textile products, the textiles uniforms worn by the existing health care workers so far have been made of cotton fabrics, whose cleaning process includes the high-temperature washing and chlorine sterilization to achieve sterile conditions before reuse. In going around and inspecting wards, physicians and nurses can not protect against bacteria attached to the hospital garments, thus MRSA or other microbes contaminated in ward A will be spread into ward B, ward C, so that the garments become the vehicle of nosocomial infections. This abnormal migrating infection phenomenon causes care and attention of Europe ECDC, the U.S. CDC and other government disease control departments.
In order to overcome the threat of MRSA bacteria on hospital-acquired infections, and the serious impact on patient health, and to improve the maintenance of the hospital environmental protection, an appropriate antibacterial textile is the EU R&D project to overcome the bacteria migrating infection phenomenon, relatively the multi-aspect searches for anti-MRSA antibacterial textiles are also being carried out in U.S.
The manufacturing and application development technology of the regular rayon fibres (or viscose fibres or regenerated cellulose fibres) has been known for more than a century, the said rayon fibres are made from a natural cellulose (wood pulp, cotton linter, etc.) via alkalization, xanthation to become cellulose xanthate, and then dissolved in the sodium hydroxide solution to produce viscose, which is filtered, ripened and extruded through a spinneret into the spin bath which contain sulfuric acid and zinc sulfate, then to obtain rayon tow, and finally stretched, cut, aftertreatment processed and dried to become a rayon fibre.
This rayon fibre can be used alone or with cotton, polyester, wool, nylon or acrylic fibre and other fibres at different blending ratios according to the required purposes. Physical and chemical properties of the rayon fibre are similar to those of cotton, the said rayon fibre exhibits good water absorption, good dyeing ability and comfort touching characteristics, but the dry tenacity (2.4 to 2.8 g/d) is poor, especially in the wet tenacity is only 50˜60% of the dry tenacity, thus the resulting clothes tend to be deformed after washing. To overcome the insufficient tenacity of the above-mentioned rayon fibre, the advanced technology to produce a high tenacity rayon (2.8˜3.2 g/d) and even a HWM rayon (3.8˜4.2 g/d) are developed, making the tenacity thereof comparable to that of cotton, the rayon fibre tenacity deficiencies shortcomings are greatly improved to expand the application scope of HWM rayon in high function and fashion clothing.
Chitosan is derived from the shells of natural shrimps and crabs, which is treated to be a polymer with two biological characteristics including the collagen in the tissues of higher animals and the fibre in the organization of higher plants, and having a good adaptability to animals and plants. Chitosan decomposes in vivo by the action of enzymes, shows a compatibility between cells in vivo, thus exhibits low antigenicity, a great adsorption capacity of serum protein and other blood components, it is a non-toxic, odorless, biocompatible and biodegradable natural polymer antibacterial agent, therefore chitosan is recognized as an environmentally friendly safety green product in the 21st century.
Textiles with antibacterial or perspiring wicking, UV resistance, insulation properties and other functions have been developed, promoted and applied one after another, wherein the antibacterial agent used for antibacterial textiles includes quaternary ammonium salt, silver ion, photocatalyst or organic halide and so on, although textiles with the use of these antibacterial substances show antibacterial effects, when they are used in personal clothing or accessories, more or less bring about the human skin allergies or irritations, and their discard after use also pollutes the environment at the risk of causing environmental problems.
U.S. Pat. No. 5,756,111 and Japanese Patent Application—HEI-SEI No. 8-92820 reveal “the chitosan fibre and method of making the structure thereof”, the technical manufacturing steps includes natural shrimp and crab shells→chitin→alkalization→xanthation→chitosan viscose, namely, the said chitosan powder of low deacetylation having the particle size below 4 mm is alkalized and xanthated similar to a rayon process reaction, the resulted chitosan viscose is added to the raw viscose made from a rayon process, and then the chitosan-containing rayon fibre is made from a general rayon manufacturing process, its tenacity is 2.4˜2.8 g/d, similar to that of the regular rayon fibre. Owing to the low DAC chitosan, it generally exhibits low antibacterial rate against Staphylococcus aureus (53% antibacterial rate), thus this low DAC chitosan can be used only in the sanitary of the general personal clothings.
The general clothing of health care workers have been made from chitosan with DAC 70 to 85%, which is dissolved in an organic acid, and post-treated on the surface of a fabric; or 70 to 85% DAC chitosan is mechanically grounded into 100 mesh or finer particles, and added to a synthetic resin to become an adhesive, which is thoroughly mixed and used as the post-processing coating for the fabric. While such post-processing coating for the fabric surface has a little antibacterial effect, its antibacterial effect disappears shortly or decays after several washings, and the chitosan antibacterial agent coated fabric easily loses the original fabric physical properties such as softness and luster.
In view of the above, after several trial and error, research and investigation, the present inventor finds that firstly, DAC of chitosan is increased to more than 90%, then the resulted deacetylated chitosan is dissolved in acetic acid and regenerated by caustic soda to nanoparticle grade chitosan and become a chitosan antibacterial agent slurry having an average particle size of 100˜600 nm, added to HWM rayon viscose with mixing, a chitosan containing HWM rayon fibre having a tenacity of 3.8˜4.2 g/d is produced via a HWM rayon manufacturing process to improve the insufficient tenacity defect of the regular rayon fibre, meanwhile nanoparticle chitosan antibacterial functional groups and HWM viscose cellulose hydroxyl groups are combined to form hydrogen bonds, the resulting fully integrated chitosan antibacterial HWM rayon fibre is spun, woven to be able to overcome MRSA growth and migrating infection phenomena, which is quite different from the process and the function revealed in U.S. Pat. No. 5,766,111, therefore the present invention is completed.